1. Field of Invention
The invention relates to a method of determining an error rate during a data transfer in a mobile radio system and also to a testing device.
2. Related Technology
In a third-generation mobile radio system, data are transferred in packets. For this purpose, the physical transfer channel is divided into consecutive signal frames that have in turn time slots as subdivisions. Each of said time slots subdivides a signal frame into a specified number of transfer blocks. In this connection, a plurality of mutually corresponding transfer blocks in consecutive signal frames is used in each case for the transfer of a data subflow. Every transfer block of a signal frame therefore transfers a portion of the total data transferred. Consequently, a plurality of data subflows is transferred in so-called concurrent processes between the base station and the mobile radio devices communicating with it.
In order to determine whether the transfer of an individual transfer block was error-free, a confirmation signal is sent back by the subscriber receiving the transfer block. The confirmation signal is a positive confirmation signal for the case of correct reception or a negative confirmation signal for the case of an incorrect reception, respectively. To test devices in the mobile radio system, said confirmation signals are recorded and an error rate is determined from the ratio of the negative confirmation signals to the total number of confirmation signals. In the case of the known procedure of the method as it is described in the 3GPP standard, a fixed transport format is used for this purpose in which all the data subflows are therefore transmitted with a common set of parameters. This has the disadvantage that it is necessary to wait a complete run of this test loop to determine an error rate that occurs in the case of a different transport format. In addition, the test method is static since the mobile radio device addressed in consecutive transfer blocks has in each case to receive and decipher a transmitted signal transmitted with the same parameters. Consequently, additional errors that occur in a dynamic process, that is to say with varying transport formats, are not detected.
The invention provides a method as well as a testing device that make possible the simultaneous determination of error rates for different transport formats.
The invention provides a method of determining an error rate during a data transfer in a mobile radio system having at least one transfer channel in which a plurality of data subflows is transmitted, comprising the following method steps: generating the plurality of data subflows by a signal generator unit, specifying transport formats individually for each data subflow, transmitting the data subflows in a number of associated transfer blocks in each case to a device to be tested by a testing device, receiving and evaluating the transfer blocks by the device to be tested and sending back a positive or negative confirmation signal for every transfer block, and determining at least one error rate from the received confirmation signals of all the data subflows by the testing device. The invention also provides a testing device for determining an error rate during the transfer of data in a mobile radio system, wherein the testing device comprises a signal generator unit for generating a plurality of data subflows, a configuration block for specifying transport formats individually for every data subflow, a transceiver for transmitting the data subflows in a number of associated transfer blocks in each case and for receiving a positive or negative confirmation signal, and an evaluating unit for determining an error rate from the received confirmation signals.
In the case of the method according to the invention, the testing device first generates a plurality of data subflows by means of a signal generator unit. A set of transmission parameters is then specified individually for each of these data subflows by a configuration unit. In this connection, each set of transmission parameters defines a particular transport format with which the respective data subflow is transmitted. The data subflow is transmitted in each case in a number of associated transfer blocks by a transceiver unit in the testing device. The device to be tested receives the transfer blocks and evaluates them. During the evaluation the data transferred in the transfer blocks are checked for correct transfer and, accordingly, a positive confirmation signal is sent back in the case of correct transfer or, respectively, a negative confirmation signal in the case of incorrect transfer. The testing device receives the confirmation signals sent back by the device to be tested and determines therefrom an error rate for the device to be tested.
In the case of the method according to the invention, it is advantageous that the device to be tested is additionally loaded in that the transport format may vary from one transport block to the next transport block. On the one hand, this increases the loading on the mobile radio device so that a realistic value for an error rate is determined even in the case of a combined evaluation of all the confirmation signals over all the data subflows, and on the other hand, it is possible to determine an individual error rate for every data subflow that is transmitted with a particular transport format, that is to say with a specified set of parameters.
The following description describes various preferred embodiments of the method according to the invention as well of the testing device according to the invention.
In particular, it is advantageous to determine an error rate individually for every data subflow by means of separate evaluating blocks in an evaluating unit. In this connection, the individual error rate gives an indication of whether, for example, an accumulation of detection errors can be correlated systematically, for example, with a chosen type of modulation.
Furthermore, it is advantageous to specify for each of the data subflows the maximum number of repetitions of the transfer block that are re-transmitted after a negative confirmation signal is sent back before the transfer block is discarded. Consequently, a redundancy version sequence can be separately specified for every data subflow. That makes it possible to eliminate effects that result from the repeated transmission of the same data content.
It is a further advantage to specify by means of a configuration block which transfer blocks are how often repeatedly transferred, in which connection, just like the redundancy version used, said repetition is specified independently of a confirmation signal.